getAnnotationAsync
abstract fun getAnnotationAsync(@IntRange(from = 0) pageIndex: Int, objectNumber: Int): Maybe<Annotation>
Returns annotation with certain object ID on the page if it exists, asynchronously.
Return
An instance of Maybe that either emits the requested annotation in `onSuccess()` or terminates with `onCompleted()` or `onError()`.
Parameters
pageIndex
Page index of the page where the annotation is.
objectNumber
Object number of the annotation to retrieve.